upgraded 11.04 to 12.04: now system freezes up when i use any program that requires the internet examples: ubuntu software center, google earth, youtube, synaptyc

i have downloaded ubuntu 12.4 upgrade from 11.04 off the update manager, and now when i use ubuntu software center it freezes up and will not load...

when i use google earth it will load but will freeze up soon after...

when i try to watch a youtube video it will freeze up soon after it starts to play...

igoogle page is very slow to load and respond...

and now i cant get to any of my hidden apps. ,system says they are already there when i try to redownload them , i have tried many searches on the dashboard feature for my apps. but i always get "no matches found" as a search result...

i never had any of these problems before i downloaded the 12.4 upgrade...

there could be problems with other apps. but i wont know till i find them...

p.s. with all these problems my computer is now an oversized paper weight...

i also downloaded 12.4 on to disc to try and wipe the hard drive clean and start fresh but got nowhere with it